Enterovirus 68 among Children with Severe Acute Respiratory Infection, the Philippines

TOC summary: Enterovirus 68 was found in 21 children with severe pneumonia

Detection of human rhinovirus C viral genome in blood among children with severe respiratory infections in the Philippines.

Human rhinovirus (HRV) C was recently identified as the third species of HRV using a molecular technique. Infections caused by previously identified HRVs (A and B) are thought to be limited to the respiratory tract; however, pathogenesis of HRVC is still largely unknown. A total of 816 nasopharyngeal swabs from hospitalized children with severe respiratory infections in the Philippines (May 2008-May 2009) were tested for HRV by reverse transcription polymerase chain reaction (RT-PCR), and 243 samples (29.8%) were positive for HRV. Among these patients, serum samples were also tested to determine whether specific HRV species were associated with viremia. Only 30 serum samples (12.3%) were positive for HRV. However, the HRV positive rates were different among HRV species, 3% (4/135) for HRVA, 0% (0/25) for HRVB, and 31% (26/83) for HRVC, and were the highest on 2 days after the onset of symptoms. These results suggest that HRVC may have a different pathogenicity and can more commonly cause viremia than HRVA and HRVB. Serum positive rates for HRV are affected by age, i.e., higher positive rates for those aged 1 year or more. HRVC that were detected from serum exhibited the same level of sequence diversity as those positive only for nasopharyngeal samples in phylogenetic analysis. However, all HRVA which were detected from serum were clustered in a monophyletic clade based on their 5' non-coding region (NCR) sequences, which is closely related with a certain HRVC genotype (A2) in 5'-NCR. This finding suggests that the 5'NCR region may be associated with viremia

HRV RNA detection in serum by RT-PCR based on number of days after onset.

<p>S-1 and S-2 indicate serum samples that were collected upon admission (S-1) and 3 days after admission (S-2). Date shown is the sampling date measured from onset of symptoms. Only PCR samples positive on S-1 were proceeded for the next analysis on S-2. The positivity rate was calculated with total (S-1+S-2) positive and negative numbers.</p

HRV RNA positivity in sera among patients positive for HRV in nasopharyngeal samples.

<p>First serum samples were collected on the day of admission (S-1). Second serum samples were collected 3 days after admission (S-2). OR is the odds ratio calculated with each species and the rest of the groups as the point of reference.</p><p>*p<0.01,</p><p>**p = 0.05.</p

SpO2 by age groups with and without HRV RNA in serum.

<p>S+ and S− indicate RNA serum positivity and serum negativity, respectively. Bar indicates the range between maximum and minimum values. Thick bar indicates interquartile range. Median and outliers are shown as a lateral bar and asterisk, respectively. ^†p<0.05, ^{† †}p<0.01.</p

HRV RNA positivity in sera by age group.

<p>OR is odds ratio calculated with each age groups and the rest of the groups within specie as the point of reference.</p

Phylogenetic tree of VP4-VP2.

<p>Black open circle indicates the HRVs detected only from nasopharyngeal swab samples. Red circle indicates the HRVs detected from both nasopharyngeal swab and serum samples. Phylogeny was inferred using NJ method on MEGA 4.1.</p

Molecular Characterization of Human Respiratory Syncytial Virus in the Philippines, 2012-2013

<div><p>Human respiratory syncytial virus (HRSV) is a major cause of acute lower respiratory tract infections in infants and children worldwide. We performed molecular analysis of HRSV among infants and children with clinical diagnosis of severe pneumonia in four study sites in the Philippines, including Biliran, Leyte, Palawan, and Metro Manila from June 2012 to July 2013. Nasopharyngeal swabs were collected and screened for HRSV using real-time polymerase chain reaction (PCR). Positive samples were tested by conventional PCR and sequenced for the second hypervariable region (2^nd HVR) of the G gene. Among a total of 1,505 samples, 423 samples were positive for HRSV (28.1%), of which 305 (72.1%) and 118 (27.9%) were identified as HRSV-A and HRSV-B, respectively. Two genotypes of HRSV-A, NA1 and ON1, were identified during the study period. The novel ON1 genotype with a 72-nucleotide duplication in 2^nd HVR of the G gene increased rapidly and finally became the predominant genotype in 2013 with an evolutionary rate higher than the NA1 genotype. Moreover, in the ON1 genotype, we found positive selection at amino acid position 274 (p<0.05) and massive O- and N-glycosylation in the 2^nd HVR of the G gene. Among HRSV-B, BA9 was the predominant genotype circulating in the Philippines. However, two sporadic cases of GB2 genotype were found, which might share a common ancestor with other Asian strains. These findings suggest that HRSV is an important cause of severe acute respiratory infection among children in the Philippines and revealed the emergence and subsequent predominance of the ON1 genotype and the sporadic detection of the GB2 genotype. Both genotypes were detected for the first time in the Philippines.</p></div